"I'm not worried a bit that I'll be able to stand on the stage with Barack Obama and draw a very bright line," Perry said.

The Texas governor, driving for front-runner status as the most viable conservative in the wide-open field, offered up samples of the scathing rhetoric he uses against the president, from the economy to war policy and personal credibility. It's part of his effort to win over voters who are weary of recession and resentful of powerbrokers.

The tough talk came as Perry manages the fallout from his debate performances and all of the GOP candidates fight to lead the pack in Iowa just two months before the first voting of 2012 begins there.

There is no clear leader in that contest. A Des Moines Register poll on Saturday showed former Godfather's Pizza CEO Herman Cain at the head of the pack, with the support of 23 percent of respondents. Ex-Massachusetts Gov. Mitt Romney was next with 22 percent.

Perry, who rated just 7 percent in that survey, has taken a particularly steep fall since announcing his candidacy in August, struggling through parts of five debates and dogged especially by Romney.

How, he was asked on "Fox News Sunday," would he perform against the erudite Obama in a general election next year?

What counts, Perry said, is how a candidate would govern.

"We got a great debater, a smooth politician in the White House right now, that's not working really good for America," Perry said.

Perry plans to attend of the debates now scheduled in November as well as a December one. "With as many debates as we got coming up, I may end up being a pretty good debater before it's all been said and done," he said.

On Iraq and Afghanistan, Perry accused Obama of pursuing an "aimless foreign policy" by making big decisions without adequately considering the advice of his commanders. He said the president has endangered Americans on the ground by announcing that U.S. troops would leave Iraq by year's end.

"He has lost his standing from the standpoint of being a commander in chief who has any idea about what's going on in those theaters," Perry said.

On the leading domestic issue, Perry said the president has "taken an experiment with the American economy and turned it into absolute Frankenstein experience."

Cain piled on the president, too.

"A responsible commander in chief" would have done more to seek out the counsel of the military's ground commanders before agreeing to pull all troops out of Iraq, Cain said. Doing that leaves a "power vacuum," he added.

"It also leaves it unclear as to how we are going to deal with other nations," Cain said on CBS' "Face the Nation."

The U.S. deadline to pull troops out by the end of 2011 was originally set by President George W. Bush. Obama decided to move ahead with the plan after Washington and Baghdad couldn't agree on the conditions for keeping a small contingent of U.S. troops behind to train Iraqi forces.

For his part, the president has mostly stayed out of the GOP nomination fight.

"I'm going to wait until everyone is voted off the island," he told "Tonight Show" host Jay Leno earlier in the week.

But a top adviser, David Plouffe, went after Romney, the early front-runner in the race. Plouffe, who managed Obama's 2008 campaign, said Romney has "moved all over the place" on issues from abortion to gay marriage over his career and might not have firm enough convictions to make the tough decisions as president.

"You get the sense with Mitt Romney that if he thought it was good to say the sky was green and the grass was blue, to win an election, he'd say it," Plouffe said on NBC's "Meet the Press."

It's not yet clear which of the Republicans might survive the nomination fight. While Cain "seems to have tapped into something," Plouffe said he found it interesting that "Romney continues to have 75, 80 percent of his party looking somewhere else, and so it'll be interesting to see if he can turn that around."

The Romney campaign shot back by saying Obama "can't run on his abysmal economic record and he is desperate to distract from the historic loss of middle-class jobs that has occurred on his watch. Americans won't be fooled by false and negative attacks."

Republicans in Iowa aren't leaning toward any one candidate, even though Romney's essentially been running for president since losing in the state in 2008.

Despite his showing in the Iowa poll, Cain trails both Romney and Perry in fundraising by the millions.

Perry is starting to focus on Iowa with a new ad, and on Sunday, he hit Romney for being on both sides of debates over gun control, abortion and gay rights.

"I have been a consistent conservative," Perry said. "I don't get confused with just telling the truth."